Optimization of agitation for production of swainsonine from Metarhizium anisopliae in stirred tank and airlift reactors

The optimal agitation rate for production of swainsonine from Metarhizium anisopliae grown in batch stirred tank reactors (2 to 20 l) was 400 rpm with a mixed hyphal and pelleted morphology where the specific swainsonine production rate was 9×10−2 mg g−1 cell dry wt h from 87 to 142 h. Culture of the fungus in a 6-l airlift reactor produced ‘loose’ pellets and the production of swainsonine started at least 24 h earlier than in the stirred tank reactor. The final yield (5.9 mg swainsonine g−1 cell dry wt) after 168 h in the airlift reactor was 18% less than those obtained in the stirred tank reactor with an agitation rate of 400 rpm.